Global Geodetic Strain Rate Model project

Earthquakes release accumulated crustal strain, and therefore strain rate is a proxy for earthquake potential. Moreover, one can use strain to assess whether the estimated fault slip rates and earthquake activity rates are consistent with the long-term strain accumulation measured from GPS.

The project on the Global Geodetic Strain Rate Model uses a budget of 250.000 Euro and a 24-month duration and has the following main goals: 
1. Create a uniform Global GPS velocity database
2. Update, expand and improve the Global Strain Rate Model (of 2004)
3. Disseminate and visualize the results

These goals will be achieved by means of: 

  • analyzing data of 4000+ continuous GPS stations worldwide and determining secular horizontal velocities;
  • adding published velocities from mainly campaign-style observations (100+ studies);
  • using a new GPS velocity database to update the Global Strain Rate Model (GSRM) of 2004;
  • using focal mechanisms, and active fault traces for constraints.

The GSRM will be significantly improved. The figure compares GSRM v1.2 of 2004 (left) and the new model (right). The grid cell resolution for GSRM v. 1.2 was 0.5° by 0.6°, for the model on the right it is 0.15° by 0.15°. The target resolution for all plate boundaries proposed here is 0.2°by 0.2°. [Note: GSRM v1.2 did not include faulting information to delineate zones of weakness in the interpolation of the GPS velocities. Such constraints will be included for the global GSRM, whereby faulting data compiled by the “Global Active Fault and Seismic Source Database" project is being used].

Read more on the state-of-the-art and the background of the project.

Consortium
The project's tasks are overseen by Principal Investigator Corné Kreemer, from the University of Nevada, Reno (USA). The consortium consists furthermore of three additional international experts: Nicolas Chamot-Rooke from the Ecole Normale Supérieure, Paris (France), Chinese Earthquake Administration (China) / UCLA, California (USA), and UNAVCO, Boulder (USA). Each of these partners, in cooperation with their team will cover part of the work.

Pacific-North America plate boundary, Americas, and western Pacific Corné Kreemer
Europe, Mediterranean, the Middle East and East African Rift Nicolas Chamot-Rooke
All of Asia Zheng-Kang Shen
Data archiving & model visualization Francis Boler

Currents Developments
The project has recently taken off, and the consortium is now working on the following steps:

  1. evaluate whether they could create one global model at a high resolution or whether it needs to be broken up into submodels with varying resolution
  2. define rigid plate geometries (and thereby the deforming plate boundary zones)
  3. assess temporal decay of postseismic GPS time-series
  4. compile focal mechanisms from around the world
  5. download and process GPS data from some networks that had not been considered before
  6. evaluate different ways how seismicity rates can be used as apriori estimates of the expected strain rates (needed in preparation of the inversion of the GPS data).

Presentations

Contact
Corné Kreemer is the consortium’s main contact point. He can be reached at kreemer[at]unr.edu

 

       
GEM Foundation | Via Ferrata 1, 27100 Pavia, Italy | info@globalquakemodel.org | Tax Code: 96059180180